The present invention is directed to a heat exchanger having a ventilator wheel or fan, in particular a radial ventilator wheel or fan, a burner and at least one heat exchanger tube which is allocated to the burner and which tube surrounds a portion of the ventilator fan.
A heat exchanger having a heat exchange tube which surrounds a portion of a radial fan is disclosed in EP 0 526 768 B1. This device is used to cook foodstuffs in a cooking chamber of a corresponding cooking apparatus.
A problem with gas-heated heat exchangers is that stresses arise due to the high temperature, which stresses, on the one hand, must be absorbed or relieved in the tubes and, on the other hand, these stresses load the tube, in particular at the fastening points on the housing, frame or the like of the apparatus. At the same time, a high efficiency of the heat exchange is to be sought. For this purpose, EP 0 526 768 B1 proposes that the heat exchanger tube is routed in a spiral shape about the ventilator wheel, and this produces a more uniform heat expansion of the heat exchanger tube to occur, and, thus, simultaneously optimizes the heat transfer. However, there remains the problem that, in addition, the fastening points of the heat exchanger tube to the housing wall or the like are still placed under stress.